1. Field of the Invention
The present invention relates to computer networks. More particularly, it relates to an automatic multi-rate wireless/wired computer network using a combination of wireless communications and an AC power network.
2. Prior Art
The ability to provide cost effective performance solutions for computer networks is consistently being sought by the computer industry. To date, there is not a single device on the market that can handle even the simplest task of wireless control in a broad sense. There are a few single application products that address very specific areas such as wireless mice, or wireless LAN.
The wireless products that have been brought to market are unreliable, and are not as good as a wired product, no matter what their claim. In addition, the automation of these products is not existent. That is, they generally require extensive user intervention to install, configure and get running. In addition, the market has demonstrated that network systems, and additional implementations must be transparent to the user.
Currently, there is not a product on the market that allows the use of the appropriate radio solution (i.e., speed MAC/protocol for a particular need that is flexible enough to cover most other needs as well.) For example, a user does not need a high cost radio and associated elements for low cost type applications (e.g., a mouse), but that is necessary for high-speed LAN access. Thus, there is a need for these different systems to be rolled into one, such that multiple modulation schemes for the varying complexity of devices can be implemented in a single piece of hardware, and whose cost is proportional to the function currently being added.
Historically, there are a limited number of modulations available and systems are typically built around one. Typical modulations used include; AM. And the related QAM FM, and the related FSK, GMSK, MFSK PSK and the related BPSK, QPSK, and M-ary PSK. Within the confines of the FM domain are the related FSK, GMSK, and M-ary FSK. In addition, the PSK modulation family is directly related to FSK via mathematical relation of differentiation or integration for the reverse relation.
Beyond these modulations, there is another family now popularized as Spread Spectrum. These have the properties of robust communications while in harsh electronic environments, such as near other radio systems, or interference such as a microwave oven, etc. They also allow transmission of higher power levels since their output is xe2x80x9cspreadxe2x80x9d over many frequencies. Essentially, there are two spread spectrum modulations, both of which are related to the FM and PSK families discussed earlier. The FM relation is what is called Frequency Hopping (FH), whereby data is mapped into the frequency domain and spread over 80 or more frequencies as illustrated in FIG. 1. The pseudo random mapping is a known sequence to both the transmitter and receiver, therefore the receiver can un-map the hopped frequencies back to the original data sequence. The second family of PSK related modulations is called Direct Sequence Spread Spectrum (DSSS). Here the original data sequence is re-mapped into phase changes rather than frequency changes. These show up in the frequency domain as looking like a Sinc function or sin x/x as shown in FIG. 2.
The FCC imposes certain restrictions on the use of both transmitted power and bandwidth. Power is related directly to the operable distance a device can work over, while bandwidth affects the data rate or speed of communications. One can only push the data rate up until the limit of the FCC bandwidth of a particular band is reached, then additional techniques need to be implemented to go beyond that, such as higher complexity modulations like M-ary PSK, or M-ary FSK or data coding techniques.
Cost sensitivity is also a clear market driven requirement. The cost must be proportional to the function the system provides. A system that can provide simple mouse interface must not cost much more than one would have to pay for the wired equivalent, yet the system must be expandable to higher level of function and speed with proportional cost.
Thus, it is apparent that there is a need for a wireless computer system which includes both protocol and hardware, which is capable of multiple modulation schemes and is simple in setup, operation and cost. The network must be expandable as the user requires, and must be transparent to the user. This means, after software installation, the user does nothing except turn on the components and they do the work of configuration within the wireless environment around a computer and the AC power network. The computer will be able to implement the simplest of tasks such as the wireless mouse and joystick to the more complex task of wireless local area networks.
It is therefore an object of the present invention to provide an automatic multi-rate wireless/wired computer network that creates both a wired (via AC power line) and a wireless network (via radio) around the computer with which new devices can be seamlessly added, without significant human intervention.
In order to achieve the above object, network boxes and respective protocol are implemented into an indoor environment such as a home or office. According to an embodiment of the invention, an intelligent RF field is created around the computer system and the entire AC power network of the indoor environment. Through the use of radios and the AC power network as both a receiving and transmitting antenna, and the support of several wireless communication protocols, the network system enables the implementation, connection and control of a diverse group of products to the network without requiring user intervention and/or configuration.
To implement the network according to an embodiment of the invention, a master network box is connected between a master computer and the indoor AC power network through connection to an AC outlet. The network box creates the RF field that is the backbone of the network. Additional network boxes, or appliance boxes, are added to other appliances in the indoor environment which enable those appliances to be controlled and operated through the master computer. The appliance boxes include an AC power connection, and can include a data bus (e.g., PCI or USB) for the two way communication of data between the network and the appliance to which it is connected. In an alternative embodiment of the invention, the appliances themselves can be fabricated with the network connection protocol contained therein, and a data bus port contained thereon.
The master network box and the master computer connected thereto are capable of communication on various channels to accommodate communication with a wider variety of additional devices. The communication system implemented by the master network box include MAC (media access channel) protocol, the physical media to transport information, and the modulation method for transmitting over the media. The master network box with master computer supports the following modulation functions: 1) low data rate FSK channel communication; 2) higher data rate 4-level FSK channel communication; and 3) time/data critical spread spectrum communication channels. In addition, the master network box provides the AC power line communications link. These four functions are based on four separate transceivers in the master network box, each occupying a specific number of channels to meet the FCC rules for its band.
In an embodiment of the present invention, the use of multiple modulations in hierarchical form, allows a communications network to be built in elements, beginning with either simple or complex functions, but always with the minimum hardware (i.e, cost and simplest implementation, to accomplish a particular function). Through the use of software programmability, multiple modulation techniques can be employed within a single piece of hardware.
An appliance box is connected between the AC power supply and all appliances in the household to be controlled and implemented into the network. When a new system component is added with the required connection box and is within the confines of the created field, it is automatically found and registered within the system. These components include, but are not limited to, low data rate items such as mice, joysticks, medium data rate items such as keyboards, POTs modems, phones, printers, cameras, and high data rate items such as LANs, disk drives, and printers.
In another embodiment, a PDA device, (e.g., cordless phone or cellular phone) can be used to contact the master computer either through a modem and telephone line connected thereto, or if within the specific range, through the RF field created by the radios and/or the AC power network. The PDA device can enable the user to use voice commands or DTMF commands to control features of the network from remote locations, such as, for example: turning on selected lights; starting an oven to prepare a meal; activating or monitoring security systems, watering the lawn, controlling a VCR to record a particular program; and environmental control over the indoor environment. In other embodiments, the system can include RF ID tags associated with various devices such that when the device enters the RF field emanating from the AC power network, the device is automatically registered in the master computer, and any information relating to that device can be accessed through the master computer. One could envision home inventory done this way.
Each appliance box includes a unique registration identifier for purposes of selectively identifying the connected appliance, and providing the necessary communication protocol to the master computer. This identifier code includes enough information for the master to know what class of device it is, and what communication protocol it prefers. The number sequence of the identifier code classifies it into certain communications categories, such as, but not limited to, single or bi-directional communications, low speed FSK rates, high speed low power FSK, high power spread spectrum communications etc. The registration identifier will include information as to the remote device""s ability to back off in data rate, and also includes information as to whether a remote device requires asynchronous or Isochronous communications (i.e., can tolerate delays in the exchange of information or must have essentially continuous service as in the case of voice). Additional coding is used to help the data make it through the channel, such as, for example to provide the master with a way to synchronize itself to the remote device and know whether an error in the received data is made. To allow for synchronization, there is a pre-amble added to the sequence of bits.
The use of the AC power line radiating between 1 and 30 MHZ and picked up by RF system and the reverse link as well, is supported by an embodiment of the present invention. The FCC allows the AC power line communication systems to radiate a certain level of RF field. In addition, the system utilizes this leakage field as part of the communication system.